Leather-stretching device.



Patented Nov. l2, |901. J. CALDWELL.

.LEATHER STRETCHING DEVICE (Applcation led Mar. 19, 1900.)

(No Model.)

THE' Nomus PETERS cu. Puonmumo.. Mamme-rc UNITED STATES PATENT OFFICE.

JOHN CALDWELL, OF MINNEAPOLIS, MINNESOTA, ASSIGNOR TO THE W. S. NOTT COMPANY, OF MINNEAPOLIS, MINNESOTA, A CORPORATION.

LEATH ER-STRETCHING DEVICE.

SPECIFICATION forming part of Letters PatentNo. 686,506, dated November 12, 1901.

Application filed March 19,1900. Serial No. 9,199. (No model.)

To tZZ whom it may concern:

Beit known that I, JOHN CALDWELL, a citiL zen of the United States,residing at. Minneapolis, in the county of Hennepin and State of Minnesota,have invented certain new and useful Improvements in Leather-Stretching Devices, of which the followingis aspecication.

My invention relates to the devices employed for engaging and holding the leather in stretching-machines and the object of the invention is to provide a series of separate and independently operated clamping or gripping devices, each of which engages only a relatively short section of the margin of the leather, and means for pivotally and detachably connecting them to the machine.

The devices for my improvements, stated in a general way, comprise a series of independent clamps, each clamp adapted to grasp only a small portion of the margin of a piece of leather and to be freely pivoted to a coupling device (preferably at variable points on the clamp conformably to itsV inclination to the line of tension) and to be separately and successively connected to a head or other proper member of a stretching-machine and eachl preferably adapted to increase its grip with the increase of tension. -Such devices are illustrated in the accompanying drawings, in which- Figure l is a vertical longitudinal section of a portion of a stretching-machine, showing one of the improved clamps in operative position. Fig. 2 is a plan view of Fig. l and shows also two modifications of the means for pivotally connecting the clamps to the coupling-bars. Figs.l 3 and 4 are side elevations of a modied construction of the clamp and coupling device, the former view showing the relative positions of the parts before and the latter after tension has been applied.

In such drawings, l designates one of the side pieces 'of an ordinary stretcher-frame, which is adapted to support a side, back, or other division of leather during the operation of stretching it and to be afterward removed from the stretching-machine and still support theleather and its holders until the leather is dried and set and taken o for use. To this frame is secured a iiXed head or member 2 for supporting one end of the leather and the devices which hold it, and a sliding head (not shown) is also provided for supporting the other end of the leather and arranged to be connected to a cross-head or equivalent moving part of a stretching-machine.

While my improvements are here shown in connection with the fixed head of the frame, itwll be apparent that they may withequallygood results be used in connection with the movable head or member.

The device for grasping the vleather and holding it consists of relatively wide and fiat pincers or grippers composed of crossed members pivoted together by a stout pintle 3 and having relatively short jaws 4 and 5 and relatively long lever-handles 6 and 7. The pivoting or hinging connection of the crossed gripper members 4 6 and 5 7 to each other is preferably made by passing the pintle 3 through knuckles, a knuckle on one of the members being fitted in the recess between a pair of knuckles on the other member, thereby strengthening the joint to withstand lateral strain. The jaws, to enable them to take a firm hold of the leather, should have teeth, tines, corrugations, or other suitable irregularities 8 on their contact-surfaces. A width of two to threeinches will be found a desirable and convenient size for the jaws. The leverhandles 6 7 may be constructed in any desirable or convenient form for connecting them to the head or otherproper part of the stretching-frame. While the jaws are in engagement with the leather the lower handle 6 rests on the surface of the stretcher-head 2, which prevents downward movement of that handle, and the strain upon the upper handle during tension tends to depress it, and thus the two handles are caused to coperate in tightening the grip of the jaws on the leather as the tension increases. As the more important use for such devices is in securing an irregular end of the leather, it is desirable that the means for connectingthem with the stretcher-head be capable of lateral adjustment or variation when the jaws are set at an inclination to the line of tension. To this end the upper handle 7, if connection is to be made with it alone, may be provided with a curved opening 9 or with suitably-lo- IOO cated separate holes 10 or pins 11. The connection of the holder with the stretcher-head may then be made by any suitable coupling device. As shown in Figs. 1 and 2, such coupling device may consist of a bar 12, having teeth 13 on its under surface for engaging serrations 14, formed on a plate 15, that is secured to the surface of the stretcher-head 2. The coupling-bars being independent of the grippers, their pivotal connection is made when desired preferably by means ot vertically-swinging arms 17, hinged to the bars and provided with hooks and adapted to engage in the elongated slots 9 or the separate openings 10 in the gripper-handles, or the arms may be provided with eyes 18 for engaging the pins 11 on the gripper-handles. In either case the connection is such as to permit free lateral swinging of the grippers at all times, as well while engaging the leather and subjected to tension as when free from the leather. When the coupling-bars have all been made to engage the serrations on the stretcher-head, they may be held down to engagement by a locking-bar 16, that is hinged to one of the frame sides and arranged to swing over the coupling devices and be connected to the other frame side. For preventing the end portion of a piece of leather 19 from rising to an objectionable extent under stress a bar 20, hinged to one of the sides of the frame, is turned down across the leather and secured to the opposite side of the frame. Forward of the bar 20 is shown one of the usual movable strips 21, resting on the sides of the frame, and which prevent the leather from sagging.

In the modified construction shown in Figs. 3 and 4 both handles 6 and 7 have curved openings 9 and both are engaged by a hook 22 of suitably curved or angular shape to tend to draw them together under tension. Any of the well-known devices for engaging such lever-handles may be employed for this purpose, and their connection with the stretcher head or member maybe madein anyconvenient way.

In practice in securing an irregular end of a strip of leather that is laid on the frame each clamp is separately placed substantially at a right angle to the edge of the portion of leather it is to hold and with its jaws in contact with the margin. The connections are then made anywhere in the curved slots, for the hooks will adjust themselves under tension, but at suitable points, if pins or separate holes are employed to properly distribute the strain at opposite sides of the connections. In Fig. 2 the arrows z indicate the direction of the pull of the leather and also the axial lines of the connecting-bars 12 and show that the extent of surface grasped by the jaws 4 and 5 is practically equal on the opposite sides of such axial lines. Such arrangement avoids unequal stress upon different portions of the jaws and the tendency of the jaws to twist under tension that an unvariable connection would produce.

It is preferable that all of the holders be arranged in their proper places on the head and caused to grasp the leather suiiciently to retain them in place before their coupling devices are connected to them, and then such connections may be made separately and consecutively and, if desired, while the machine is in operation. As illustrated in Fig. 2,either or bot-h of the holders shown as engaging the shorter portion of leather near its side (such portion being the softer and more yielding portion) may be connected to the head and put in service before the intermediate holder or holders are connected and operated. In this way different longitudinal portions of the leather that vary in rmness or condition can be stretched in succession and to different degrees.

I do not wish to limit my claims to such leather-clampin g devices when provided with means for lateral variation of their points of pivotal connection to their coupling devices, nor do I wish to limit my protection to the specific forms and arrangements of the devices shown or described, for I believe it to be broadly novel to employ a series of clamping or gripping devices adapted to engage successive marginal portions of leather and a corresponding series of coupling devices adapted t-o be separately and successively pivotally connected to such leather-holders, whereby the latter may swing freely under tension, and means provided on a stretcherhead and on the coupling devices whereby the latter may be adjusted both laterally and longitudinally upon and operatively connected to the stretcher-head.

Patentable subject-matter herein disclosed relating to the free pivotal connection of the holders to their coupling devices, whereby they may swing freely upon each other under tension, and relative to the means for connecting the latter to the stretcher-head, is reserved to be claimed in concurrently pending applications Serial No. 1,424, led January 15, 1900, and Serial No. 10,128, filed March 26, 1900, and the subject-matter of invention herein disclosed and notclaimed relative tothe meansfor varying the point of pivotal connection of the holder to the coupling device conformably to the direction of tension of the leather is reserved to be claimed in my pending application Serial No. 10,128, led March 26, 1900.

Having described my invention, what I claim is 1. The combination with a stretcher-head, of an independent leather-holder, and an independent coupling-bar adapted to be adjustably connected to the stretcher-head and carrying a hook arranged to swing in vertical direction and to engage the holder for freely pivoting it to the bar, substantially as set forth.

2. The combination with a coupling-bar IOO IIO

adapted to be adjustably connected to a stretcher head and carrying a verticallyswinging hook or like device, of a leatherholder provided with means for receiving such hook at variable points in rear of its leatherengaging devices and to be Ithereby freely pivoted to such bar, substantially as set forth.

3. A leather-holder for a stretching-machine, consisting of hinged grippingjaws, crossed lever-handles for operating them, a base or support for the lower handle, and an independent coupling device for pivotal] y and adj ustably connecting the upper handle to the machine, substantially as set forth.

, 4:. The combination with a leather-holder provided with means on its front portion for engaging the leather and having an opening in its rear portion, of a coupling device provided with a hook for engaging in such opening for pivotally connecting the coupling device to the holder, and means for adj ustably connecting the former to a member of a stretching-machine,substantially as set forth.

5. A leather-holder for a stretching-machine, consisting of hinged gripping-jaws, handles for operating them, and a pivotallyconnected coupling device for detachably securing the holder to the machine, and means provided on a handle of the holder for lateral adj ustlnent of the point of pivotal connection of the coupling device with it, substantially as and for the purpose set forth.

6. In a leather-stretching machine,the combination with a stretcher-head, of a series of independent leatherholders consisting of gripping-jaws and means for operating them to grip the leather, and a corresponding se-4 ries of independent coupling devices adapted to be adjustably connected to the stretcherhead and to be detachably and pivotally connected to the holders to permit the latter to swing freely under tension, substantially as set forth.

7. In a leather-stretching machine, the combination with a stretcher-head; of independent leather-h olders consisting of hinged grippingjaws and crossed handles for operating them, the lower handles resting on the stretcher-head; coupling devices for connecting-the upper handles to said head, and means providedon the head and coupling devices permitting the lateral and longitudinal adjustment of the latter on the former and their operative connection thereto, substantially as set forth.

8. In a leather-stretching machine,the combination with a stretcher-head, of independent leather-holders consisting of hinged gripping-jaws and crossed handles for operating them, the lower handles resting on the stretcher-head, and coupling devices connecting the upper handles to the stretcher-head, and means provided on the upper handles for lateral adjustment of the points of connection of their coupling devices with them, substantially as set forth.

9. A leather-holder for a'stretching-machine, consisting of hinged grippingjaws, crossed lever -handles for operating them, both handles being provided with. openings in curved arrangement, and a coupling device provided with a hook for engaging in said openings to connect the holder to the stretching-machine, for the purpose set forth.

In testimony whereof I have hereunto set 7 

